In computers, tape backup is the ability to periodically copy the
contents of all or a designated amount of data from its usual storage
device to a tape cartridge device so that, in the event of a hard disk crash
or comparable failure, the data will not be lost. Tape backup can be
done manually or, with appropriate software, be programmed to happen
automatically.
Tape backup systems exist for needs ranging from backing up the hard
disk on a personal computer to backing up large amounts of storage for archiving and disaster recovery purposes in a large enterprise as part of a storage area network (SAN),
usually combining a hardware and software package. For personal
computer tape backup, the Onstream USB tape drive is popular. For
enterprise tape backup, Linear Tape-Open (LTO) is an industry open standard from Hewlett-Packard, IBM, and Seagate.
Tape backup also includes the ability to restore data that has been
backed up back to hard disk storage devices when needed.
reff............http://searchstorage.techtarget.com/definition/tape-backup